Culling and relocation by humans can haunt elephant populations for decades, a new study shows, causing emotional trauma and disrupting their social education. This robs them of key survival skills later in life, an effect that could spread to future generations.
The research focuses on wild elephants in South Africa, where officials often culled adults and relocated calves as part of a wildlife-management strategy from the 1960s to the 1990s. But according to its authors, the study may also apply to other, ongoing forms of disturbance by humans, including habitat loss and illegal poaching
The loss of older relatives is obviously traumatic for young elephants, especially if they witness a mass killing. But even decades later, when they seem like well-adjusted adults, their disrupted youth can still surface in troublesome ways. Social learning is critical to young elephants, who normally pick up successful behavior patterns from older, more experienced members of their herd. Without such role models, generations of ecological knowledge may be lost, leaving some elephants to improvise their survival strategies.
Part of the study was conducted in South Africa's Pilanesberg National Park, where a population of orphaned elephants
was imported in the 1980s and '90s after their elder herd members were culled at Kruger National Park. Researchers tested their cognitive abilities by playing recordings of various elephant vocalizations to target families within each population. The goal was to mimic different types of social threats, letting the researchers compare orphaned elephants' reactions with those of elephants from less traumatic backgrounds living at Amboseli National Park in Kenya.
To conduct these tests, the researchers parked their Land Rover about 100 yards away from an elephant family and broadcast an array of 10- to 20-second elephant calls. Elephants in both groups were exposed to a set of familiar and unfamiliar calls, as well as 50 recorded sounds that simulated calls from elephants of various sizes and ages.
Photo: Alexander Joe/AFP/Getty Images
The elephants' reactions to these calls were assessed in four categories: occurrence of defensive bunching, intensity of the bunching response, prolonged listening and investigative smelling. The researchers filmed all the reactions (see video below
) and coded them, allowing a comparison of the orphaned and non-orphaned groups.
The goal was to learn whether their different upbringings affected the elephants' decision-making when confronted with a potential threat. If a recorded call really did herald an older, unfamiliar and more dominant female, for example, the herd might need to adopt some defensive posturing or possibly even flee to safety.
The non-orphaned Amboseli elephants tended to act appropriately. Upon hearing an unfamiliar call, they typically froze in place, perked their ears and raised their trunks, letting them listen and sniff for more information. They then bunched together and turned toward the Land Rover, forming a wall led by the herd's matriarch. "You get the feeling they really know what they're doing," study co-author and University of Sussex animal psychologist Karen McComb tells ScienceNow
. "They have very coordinated responses."
The Pilanesberg elephants, on the other hand, seemed lost. One family fled half a mile after hearing the call of an elephant they all knew, while others seemed obliviously unfazed by the call of an older, unfamilar female. "The pattern there was no pattern at all; their reactions were completely random," McComb says. "You might think because of their history that they were just more accepting of strangers. But it wasn't that. They simply failed at picking out the calls of older, socially dominant animals."
Photo: Cameron Spencer/Getty Images
Instead, McComb and her colleagues suspect the Pilanesberg elephants lack important social knowledge they would've learned from their culled elders back at Kruger National Park. The eldest female normally serves as a herd's matriarch, gathering vital information over her lifetime and eventually teaching youngsters things like how to greet relatives and how to deal with strangers. Since the orphaned elephants grew up without that cultural context, they missed those lessons and may even pass on their misguided behavior to future generations, the researchers report in the journal Frontiers in Zoology
Knowing how to interact with other elephants could affect their survival, the researchers note, since avoiding conflict is a major part of living in a complex society where such run-ins are common. "We previously knew very little of how crucial skills of communication and cognitive abilities that are at the basis of complex societies might be affected by disruption," McComb says in a press release
about the study. "While elephants in the wild can appear to recover, apparently forming quite stable groups, our study was able to reveal that important decision-making abilities that are likely to impact key aspects of the elephant's social behavior may be seriously impaired in the long run."
And while legal culling was behind the Pilanesberg elephants' issues, co-author Graeme Shannon — also a University of Sussex animal psychologist — points out that ongoing human activities like poaching, encroachment and war seem likely to cause similar threat-assessment problems. That could spell trouble not just for elephants, he adds, but also other intelligent, long-lived animals that often clash with humans.
"The dramatic increase in human disturbance is not just a numbers game, but can have profound impacts on the viability and functioning of disrupted populations at a deeper level," Shannon says. "Our results have implications for the management of elephants in the wild and captivity, in view of the aberrant behavior that has been demonstrated by traumatized individuals. The findings also have important implications for other long-lived, social and cognitively advanced species, such as primates, whales and dolphins."
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